The present invention generally relates to the field of clean room-like environments and, more particularly, to a material delivery system for such environments.
Many manufacturing or assembly processes require an environment which is free of particulates or other contaminants to at least a certain degree. Clean rooms have long been used in the semiconductor industry for the processing of wafers from which semiconductor devices are formed. Other industries which have used clean rooms include computer disk drive manufacturers. Certain disk drive parts are manufactured in a clean room environment, while other parts are manufactured and then cleaned prior to entry into a clean room for incorporation into some type of an assembly within the clean room (e.g., an actuator arm assembly).
One alternative to clean rooms which has been used at least in the computer disk drive industry is a so-called minienvironment. Minienvironments effectively are a self-contained unit which may be disposed within or outside of a clean room and which provide clean room-like air qualities. A representative example of a minienvironment is disclosed in U.S. Pat. No. 5,487,768 to Zytka et al., which is owned by the assignee of this patent application, and which is incorporated by reference in its entirety herein. Generally, a minienvironment is an enclosure of sorts which has its own forced air system for delivering filtered air into the noted enclosure. Various types of access may be provided to the minienvironment and through which this air may be discharged along with any particulates or other contaminants contained therein. These accesses or fluid interconnections with the surrounding environment are typically disposed on a lower portion of the minienvironment, and the filtered air is typically introduced into the minienvironment in an upper portion thereof.
Smaller-sized openings may be provided in the minienvironment""s enclosure to allow an operator to dispose his or her arms therethrough to retrieve parts and/or to execute some type of operation (e.g., assembly) within the minienvironment. Only the operator""s hands and possibly a portion of the operator""s arms need to meet certain cleanliness requirements with this type of minienvironment. It should be appreciated that these types of minienvironments thereby do not provide for total isolation from the surrounding environment, but instead rely on a higher air pressure within the minienvironment""s enclosure to keep particulates and other contaminants which may exist in the surrounding environment from flowing into the minienvironment through the noted fluid interconnections. The above-noted reference to an xe2x80x9cenclosurexe2x80x9d for a minienvironment would thereby include a shroud, hood, or the like which does not provide for a total enclosure (e.g., a gap may exist along a lower portion of a sidewall of the minienvironment). Some minienvironments may include a glove box or the like to further maintain the cleanliness within the minienvironment and for the above-noted types of purposes. Still other minienvironments have no access for operations personnel during normal operations within the minienvironment, but instead rely on robotic devices within the minienvironment to perform the desired operation(s) therewithin. In both of these later instances, there may be a total isolation of the interior of the minienvironment from the surrounding environment.
There are rather significant costs associated with the operation of both clean rooms and minienvironments. Simply put, the various actions which are undertaken in order to maintain the desired level of cleanliness often come at a rather significant financial cost. Both personnel and all other materials (e.g., parts to be used in an assembly being executed in the clean room/minienvironment) which enter the clean room or the minienvironment must be within the desired cleanliness level. U.S. Pat. Nos. 5,713,791 and 5,344,365 both address rather extravagant systems/methods directed to the transfer of materials to/from/within a clean room environment. So-called xe2x80x9cclean cartsxe2x80x9d have also been used to transfer materials from outside a clean room to a location therein. Known clean carts are simplistically a box with an access door on a side thereof (i.e., the top is non-removable in these units). Cleaned parts are loaded into this xe2x80x9cboxxe2x80x9d through the access door. Filtered air is simultaneously blown into the xe2x80x9cboxxe2x80x9d during loading through this access door as well. All intended discharges from within the xe2x80x9cboxxe2x80x9d at this time are also through this same access door as there are no other designed perforations in the clean cart. Once the clean cart is loaded, the door is closed to seal the interior of the same and it may then be wheeled into the clean room. Typically these clean carts are parked next to a station which uses the parts contained therein in some manner.
Numerous disadvantages exist in relation to known clean carts. One is that these clean carts consume floor space which in some cases may be at a premium. Another is that the operator must manually retrieve parts from the clean cart and provide the same to the subject workstation. Often this involves certain repetitive motions which may subject the operator to injury over time. For instance, an operator positioned on a chair at a minienvironment may have to rotate 90xc2x0 and bend over to access the parts contained within the clean cart, and thereafter rotate back to the minienvironment with the parts in hand (typically on a tray) to position them into the minienvironment. The alternative would be for the operator to get up and walk over to the clean cart which not only wastes valuable time, but possibly means positioning the clean cart at a location where there may be unanticipated impacts between the clean cart and personnel which would be undesirable in a number of respects.
The present invention generally relates to material delivery systems and, more particularly, to material delivery systems for use in clean room-like environments which include a station. xe2x80x9cStationsxe2x80x9d for purposes of the present invention include any zone or area where products are stored, assembled, subject to transport, or acted upon by any type of processing apparatus and/or operations personnel. xe2x80x9cClean room-like environmentsxe2x80x9d include clean rooms as well as minienvironments of the type discussed above.
A first aspect of the present invention relates to a material delivery system which may exist as a stand-alone unit (e.g., a portable cart, an enclosure of sorts with wheels, casters, or other transport mechanism) or which may be incorporated into the design of a given station (e.g., by being fixedly interconnected with at least a portion of the station such as a work table or the like). The material delivery system includes at least some type of enclosure which may be defined at least in part by a sidewall assembly. In one embodiment the vertical extent or height of this enclosure is such that it maybe disposed xe2x80x9cunderxe2x80x9d stations of the above-noted type. Positioning the enclosure of the material delivery system of the first aspect of the present invention in this manner reduces the space requirements in the work area at issue by taking advantage of space which is typically wasted in the above-noted types of environments and which is often thought of as being xe2x80x9cdirty.xe2x80x9d Products (including component parts) used at the station may be stored within the confines of the enclosure. In another embodiment of this first aspect of the present invention, the material delivery system includes an elevator which is disposed at least somewhere within the confines of the enclosure for moving a payload therewithin. Preferably, both of these embodiment are used in combination although such is not required. In the case of the noted combination, a payload may be stored in each of a plurality of trays which are stacked within the confines of the enclosure and raised by the elevator to a suitable height for access by equipment, operations personnel, or both at the station.
Various refinements exist of the features noted above in relation to the first aspect of the present invention. Further features may also be incorporated in the present invention as well. These refinements and additional features may exist individually or in any combination. The station with which the material delivery system of the present invention is at least interfaceable therewith may include a table top or the like on which one or more processing/assembly operations are performed. One or more apertures may extend through this table in alignment with the elevator such that product may be brought up through this aperture(s) to an upper surface associated with the table, all by an upward movement of the elevator through the enclosure. Materials present at any one of these apertures through the table may be characterized as being within a material handling zone or the like. Other areas may exist at the station as well, including one or more work areas. Materials provided to the station by the material delivery system may be transported either manually or via robotics to one or more areas throughout the station. In the case of a minienvironment, materials may be provided by the upward movement of the elevator to one or more material handling zones (e.g., by having a plurality of separate trays disposed at a common level on the elevator, by using a partitioned tray) and the minienvironment may include one or more workstations or the like.
The elevator may include a vertically movable platform within the enclosure which functions as a support surface or the like for the elevator. One or more trays may be positioned on this platform in stacked relation, in side-by-side relation, or both, with each tray typically including a plurality of parts. Both partitioned (e.g., for segregating parts within a given tray) and non-partitioned trays (e.g., for containing a plurality of the same parts) are contemplated. The area within the enclosure in which products may be stored on the platform may be characterized as a material storage space within the enclosure. Although the elevator could be configured to remove an empty tray from a certain position and replace the same with a tray having more of the desired parts (e.g., a continuous loop conveyor-like system), as will be discussed in more detail below, in one embodiment the drive assembly for the elevator of the material delivery system may include a simple lead screw-based drive assembly which includes one or more rotatably driven lead screws. In this case it may be necessary to manually remove the empty trays from the material delivery system at the station. These empty trays may be provided to a material disposal area or the like, such that trays may be characterized as being disposable.
Movement of the platform within the enclosure may be characterized as being between a lowermost and an uppermost position, with the lowermost position being disposed at least about 24 inches (60.96 centimeters) below that area where it is desired to provide the materials. With some of the materials being disposed at this elevation below the station, this emphasizes the desirability of including an elevator within the material delivery system to alleviate the need for the operator to reach down into the enclosure to retrieve product. An infinite number of positions of the elevator relative to the enclosure may be realized to tailor the material delivery system to the needs of a particular station or to a particular operator. One way to affect this movement is to have a drive assembly controller for a drive assembly (e.g., motor) used by the elevator. This drive assembly controller may be operated by operations personnel to dispose the elevator at the desired height, and thereby the product provided thereby. Simplification of one or more aspects of the material delivery system may be realized by actually maintaining the drive assembly controller at the station. As such and particularly in the case of a portable material delivery system, once the material delivery system is positioned relative to the station, all that need be done is to interconnect the drive assembly controller and the drive assembly by a communications cable or the like (e.g., plug the communications cable into the appropriate location on the material delivery system, such that the material delivery system need not include any significant electronics).
The elevator platform may also be viewed as defining an upper chamber and a lower chamber within the enclosure, with the upper chamber being available for product storage and subsequent transport by the elevator. These upper and lower chambers need not, and preferably are not, isolated from each other at all times, particularly for the case when the material delivery system is used with a minienvironment. Minienvironments typically use a forced air system which directs filtered air into the minienvironment from a location above the work surface area to direct particulates and other contaminants away from the work surface area and preferably out of the minienvironment. Preferably the material delivery system does not affect the air flows provided by this forced air system, and thereby does not significantly affect the cleanliness levels within the minienvironment. In this regard, a space may be provided about at least a portion of the perimeter of the platform to fluidly interconnect the above-noted upper and lower chambers of the enclosure. Preferably an annular spaces exist between the perimeter of the platform. Other ways of fluidly interconnecting the defined upper and lower chambers may be used, although the space about at least a portion of the platform""s perimeter is currently preferred. Flows from the minienvironment which enter the upper chamber and xe2x80x9cflowxe2x80x9d over the product therein may also flow down into the lower chamber of the enclosure.
Allowing flow from the noted upper chamber to the noted lower chamber within the enclosure reduces the effects of the material delivery system on the cleanliness of the minienvironment. Additional features may be incorporated to further reduce the potential for a disruption of the minienvironment by the presence of the material delivery system in accordance with principles of the present invention. In this regard, the enclosure of the material delivery system may include a bottom such that the lower chamber is disposed at least somewhere between the bottom and the elevator""s platform. A plurality of perforations may be included in this bottom structure. Pressurized fluid which enters the lower chamber may then be discharged from the enclosure through these plurality of perforations. This further reduces the potential for the material delivery system of the present invention adversely affecting the air quality of the minienvironment.
In at least certain instances it will be desirable to isolate the product within the upper chamber from the environment in which the enclosure of the material delivery system of the present invention is disposed. In the case where the above-noted perforations are incorporated on a bottom of the enclosure, stated another way preferably there is a way to seal these perforations off from the upper chamber. Consider the case where the material delivery system is a portable cart or the like for providing product to a minienvironment. In this regard, xe2x80x9ccleanxe2x80x9d product likely will be loaded into the upper chamber of the enclosure at a location which is outside of the area in which the minienvironment is located. Attempts will typically be made to maintain the level of cleanliness of these xe2x80x9ccleanxe2x80x9d products during this loading procedure as well. A number of features may be incorporated into the material delivery system of the present invention to attempt to maintain this level of cleanliness during the transport of the material delivery system of the present invention to the minienvironment. One such feature is incorporating a gasket on the above-noted bottom of the enclosure. This gasket may be configured to totally surround the area of the bottom having the above-noted plurality of perforations. An extension then may be interconnected with the platform of the elevator to sealingly engage with this gasket about its entire circumference. Typically, this will be the case only when the elevator is disposed in its lowermost position (e.g., when the enclosure is xe2x80x9cfullxe2x80x9d of product). After the material delivery system is xe2x80x9cparkedxe2x80x9d at the minienvironment, the platform may be raised to provide product in the above-noted manner. This movement of the platform may then disengage the extension from the gasket to allow air flow from the minienvironment to flow into the upper chamber, into the lower chamber, and then out of the enclosure through the now xe2x80x9cun-sealedxe2x80x9d plurality of perforations.
Another feature which may be included in the material delivery system and which is applicable to maintaining at least a certain level of cleanliness within the enclosure, for instance during transport of the material delivery system, is an access to an interior of the enclosure which contains product. In this regard, the enclosure may include an opening through which product may be loaded into the enclosure. This opening may be sealed by a cover or top which is removable from an uppermost portion of the enclosure in at least some respect. Both a total removal and a partial removal of this top (e.g., using a hinge to allow the top to pivot away from the enclosure) are contemplated. The top may interface with one or more flanges or the like formed on the enclosure to enhance the seal between the enclosure and the top. One or more gaskets may be included in the interface between the top and the enclosure to further enhance the seal therebetween. Compression of the top against the enclosure may also be used to enhance the seal therebetween. Any combination of these cover-to-enclosure sealing features may be used as well.
Preferably the area of the enclosure in which product is stored is at least substantially isolated from the remainder of the material delivery system of the present invention. An additional feature which relates to this issue is how the elevator""s platform interconnects with the remainder of the elevator and which is subject to a number of characterizations. Broadly stated, the mechanical interconnection(s) of the platform with the remainder of the elevator is disposed at an elevation which is below that of an uppermost surface of the platform. In one embodiment, at least one and preferably one or more of guide rods, lead screws, or both, are used to advance the platform vertically within the enclosure. The area within the enclosure through which the platform travels may be at least substantially isolated from these guide rods/lead screws. For instance, one or more vertically extending partitions maybe disposed inwardly and spaced from an adjacent portion of the enclosure so as to be disposed between the platform and each guide rod/lead screw. That is, the guide rods/lead screws may be disposed within this space or spaces between a periphery of the platform and the inner surface of the enclosure. Consider an example where the platform is at least substantially rectangular or square. One guide rod, one lead screw, or both may be disposed on one side of the platform, and one guide rod, one lead screw, or both may be disposed on an opposite side of the platform. One partition may be disposed between the platform and guide rod(s) and/or lead screw(s) on one of the noted sides of the platform to provide the desired degree of isolation, and another partition may be disposed between the platform and guide rod(s)/lead screw(s) on the other of the noted platform sides. The structure (e.g., a coupling, bracket, connecting rod, or the like) which connects the platform with a particular guide rod or lead screw may extend through a split seal (e.g., a pliable material with a slit therethrough) formed in the subject partition. In cases where the guide rod(s)/lead screw(s) are vertically disposed, so to will be the corresponding split seal(s).
The elevator includes a drive system of at least some type to advance the platform within the enclosure. One appropriate type of drive system uses the above-noted lead screw(s). In this regard, a motor may be disposed within the enclosure somewhere below the partition. At least some degree of isolation is thereby provided between the motor and the product which is on/stacked upon the platform (e.g., this further reduces the potential for the existence of the motor xe2x80x9ccontaminatingxe2x80x9d such product). Further reductions in the potential for the drive system xe2x80x9ccontaminatingxe2x80x9d the product on the platform may be realized by establishing the interconnection between this motor and the lead screw(s) somewhere outside of the enclosure. In this regard, the motor""s shaft may extend through a bottom of the enclosure, as may each lead screw used by the drive assembly. One or more pulleys may be fixed to that portion of the motor""s drive shaft which extends through and beyond the enclosure. A drive transfer member such as a continuous loop of rubber, chain, or the like may then be looped around the motor pulley and the corresponding lead screw (which may also include a pulley) to interconnect the rotating drive shaft of the motor with each lead screw. Rotation of the lead screw(s) then raises or lowers the platform which will somehow be threadably interconnected with the lead screw (either directly or indirectly). Stability of the platform during travel within the enclosure is provided by disposing rotatably-driven lead screws on diagonally opposite corners of the platform and disposing guide rods on diagonally opposite corners of the platform such that there is a single guide rod or lead screw effectively at each corner of the platform. Rotation of the lead screw(s) xe2x80x9cdrivesxe2x80x9d the platform or moves the same within the enclosure, while there is a sliding interrelation between the platform and guide rod(s).
A second aspect of the present invention relates to an improved clean cart of sorts which may be used in a filtered environment, such as a clean room, minienvironment, or the like, and such may be used in combination with those features discussed above in relation to the first aspect of the present invention. The clean cart includes a body and a cover which is removable therefrom through a cover lifting assembly. An enclosed material storage area is defined at least in part by the body and the cover. Since the clean cart is for filtered environments, the material storage area is sufficiently sealed to maintain contamination levels at least as clean as a Class 100 environment in accordance with Federal Standard 209.
Various refinements exist of the features noted above in relation to the second aspect of the present invention. Further features may also be incorporated in the second aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. How the cover lifting assembly may act on the cover to remove the same from the body is subject to a number of characterizations. The cover lifting assembly may act on the cover so as to move the cover away from the body along a substantially axial or linear path (e.g., xe2x80x9cstraightxe2x80x9d away from the body). This reduces the potential for degradation of any gasket which may be attached to the cover to provide a more suitable seal between the cover and the body of the cart since the gasket will not be exposed to any shear-like forces when removed in this manner. The cover lifting assembly may also be characterized as pushing upwardly on the cover to displace the same from the body.
The body in the subject second aspect may include at least one cover support surface, and this cover support surface may include at least one aperture which extends entirely therethrough. Preferably there is at least a pair of such cover support surfaces which are disposed on opposite sides of the body. Wheels may be provided on the lower surface of the cover to assist in removal of the cover from the body. When the cover is seated onto the body via the cover support surface(s), each of these wheels may be disposed within and extend completely downwardly through one of the apertures which is aligned therewith. These wheels may be acted upon to push the cover away from the body for purposes of cover removal, and therefore may be considered as part of the cover lifting assembly. Another function may be provided by the these wheels. Once the wheels are disposed in at least substantially co-planar relation with their corresponding cover support surface, the cover may be rolled off of the body of the cart. In a case where a gasket is attached to the lower surface of the cover to provide a desired seal between the cover and the body, having these wheels extend further away from the lower surface of the cover than the gasket will then displace the gasket from the cover support surface during this rolling motion. As such, the gasket will not be exposed to any shearing-like forces which will thereby prolong the life of the gasket.
The above-noted aperture(s) in the cover support surface(s) may be utilized to lock the cover onto the body, alone or in combination with the above-noted cover xe2x80x9cliftingxe2x80x9d function. In this regard, the cover may include at least one first latch member which extends downwardly through an aperture in the cover support surface aligned therewith. A second latch member may be interconnected with the body and further may be engageable with its corresponding first latch member so as to xe2x80x9clockxe2x80x9d the cover onto the body, or to restrict relative movement between the cover and body in at least one direction. Preferably, the noted aperture(s) in the cover support surface(s) is used to both xe2x80x9clockxe2x80x9d the cover to the body, and further to lift the cover away from the body. In this regard, a first latching and camming assembly may be interconnected with the cover and extend downwardly into and preferably through an aligned aperture in the cover support surface. A second latching and camming assembly may be movably interconnected with the body of the cart. In a first position, the second latching and camming assembly engages its corresponding first latching and camming assembly so as to xe2x80x9clockxe2x80x9d the cover onto the body in the above-described manner. Movement of the second latching and camming assembly from its first position at least toward its second position first xe2x80x9cunlocksxe2x80x9d the cover from the body, and thereafter directs the first latching and camming member upwardly through its corresponding aperture to displace the cover from the body and to allow for removal of the same. In one embodiment, the second latching and camming assembly is directed upwardly within its corresponding aperture to not only direct its corresponding first latching and camming assembly in the above-described manner, but to further provide a surface which is at least substantially co-planar with the adjoining cover support surface. This is particularly desirable where the first latching and camming assembly includes a roller for rolling the cover off the body.
More than one first latching and camming assembly and more than one second latching and camming assembly may be provided for each cover support surface. For instance and in the case where there are two such cover support surfaces disposed on opposite sides of the body of the cart, two displaced first latching and camming assemblies may be provided on the cover on one side thereof, while two displaced first latching and camming assemblies maybe provided on the opposite side of the cover. Similarly, two second latching and camming assemblies maybe disposed on one side of the body of the cart, and two second latching and camming assemblies may be disposed on the opposite side of the body of the cart. An appropriate linkage may interconnect the second latching and camming assemblies which are located on the same side of the body of the cart. Both of these linkages in turn may be activated by interconnecting these linkages with a common handle which may be pivoted in one direction to seal the cover onto the body, and which may be pivoted in the opposite direction to lift the cover from the body in the above-described manner. The handle may also be used to transport the cart from one locale to another, such as by incorporating wheels on the bottom of the cart.